The UN-backed court says they were prominent members of the junta which seized power following a coup in 1997.

Many thousands of people were killed, raped and mutilated in the 10-year war.

In their opening address, prosecutors said the evidence they would present would "show pain, agony, suffering, sorrow and grief beyond human description, understanding and reason."

They said the trial would hear evidence from young men who had their hands cut off, women who were gang-raped and children forced to become soldiers.

"In a decade of painful and horrific warfare, their intense criminal actions over a relatively short period of time took the suffering to a new dimension and traumatised an entire nation," said Chief Prosecutor David Crane of the three defendants.

Exile

Johnny Paul Koroma, leader of the junta, the Armed Forces Revolutionary Council, has also been charged, but his whereabouts are not known.

There were reports two years ago that he had been killed in neighbouring Liberia, but they were never confirmed.

Former Liberian President Charles Taylor is also wanted by the court for allegedly backing Sierra Leone's RUF rebels.

He is in exile in Nigeria after resigning as part of a deal to end Liberia's civil war.

Last week, Mr Crane announced that he would be stepping down in July for family reasons.

Unlike the war crimes tribunals for Rwanda and the former Yugoslavia, the UN-backed Special Court for Sierra Leone is based where the alleged crimes occurred and draws on both national and international law.